IS 4326

This presentation has include the overview of IS 4326:1993.

1. PRESENTED BY:- ER. DIVYA VISHNOI IS 4326:1993 (SECOND REVISION) EARTHQUAKE RESISTANT DESIGN AND CONSTRUCTION OF BUILDINGS- CODE OF PRACTICE

2. SCOPE:- This standards deals with the selection of materials, special features of design and construction for earthquake resistant buildings including masonry units timber construction and buildings with prefabricated flooring/roofing elements. Guidelines for earthquake resistant building constructed using masonry of low strength and earthen buildings are covered in separate.

3. DESCRIPTION OF CODE:- TERMINOLOGY GENERAL PRINCIPLES SPECIAL CONSTRUCTION FEATURES TYPES OF CONSTRUCTION CATEGORIES OF BUILDINGS MASONRY CONSTRUCTION WITH RECTANGULAR MASONRY UNITS FLOORS/ROOFS WITH SMALL PRECAST COMPONENTS TIMBER CONSTRUCTION

4. TERMINOLOGY:- SEPERATION SECTION CENTRE OF RIGIDITY SHEAR WALL SPECIAL FRAME BOX ACTION BAND SEISMIC ZONE& SEISMIC COEFFICIENT DESIGN SEISMIC COEFFICIENT CONCRETE GRADE

5. GENERAL PRINCIPLES (CLAUSE 4.0) LIGHTNESS CONTINUITY OF CONSTRUCTION PROJECTING & SUSPENDED PARTS BUILDING CONFIGURATION STRENGTH IN VARIOUS DIRECTION FOUNDATION DUCTILITY FIRE RESISTANCE

6. SPECIAL CONSTRUCTION FEATURES (CLAUSE 5.0) SEPERATION OF ADJOINING STRUCTURES SEPERATION OR CRUMPLE SECTION FOUNDATION ROOF & FLOORS STAIR CASE

7. TYPE OF CONSTRUCTION (CLAUSE 6.0) FRAMED CONSTRUCTION BOX TYPE CONSTRUCTION

8. CATEGORIES OF BUILDINGS (CLAUSE 7.0)

9. MASONRY CONSTRUCTION WITH RECTANGULAR MASONRY UNITS (CLAUSE 8.0) 1. MASONRY UNIT:- i ) For earthquake resistant buildings, well burnt bricks and solid concrete blocks having crushing strength not less than 3.5 MPA should be used. i i) Squared stone masonry, stone block masonry as per is:1597(part-2):1992 may also be used

10. MASONRY CONSTRUCTION WITH RECTANGULAR MASONRY UNITS (CLAUSE 8.0) 2. MORTARS:- i ) Since tensile and shear strength are important for earthquake resistance, use of mud or very weak mortar is not suitable. A mortar mix of Cement: Sand (1:6) by volume at least should be used. Ii) Where steel reinforcing bars are provided in masonry the bars shall be embedded with adequate cover in cement sand mortar not leaner than 1 : 3 (minimum clear cover 10 mm) or in cement concrete of grade M15 (minimum clear cover 15 mm or bar diameter whichever more).

11. MASONRY CONSTRUCTION WITH RECTANGULAR MASONRY UNITS (CLAUSE 8.0) WALL:- i ) The thickness of load bearing wall should not be less than 190mm and wall length should not be greater than 15m. ii) The masonry bearing wall can be built up to a maximum of four storeys. i ii) The masonry bearing wall should be properly reinforced. i v) The bearing wall should be straight and symmetrical in plan in both directions. v ) The wall panels should be checked for strength in bending and shearing.

12. MASONRY CONSTRUCTION WITH RECTANGULAR MASONRY UNITS (CLAUSE 8.0) 4. Masonry Bond:- i ) For achieving full strength of masonry, the usual bonds specified for masonry should be followed. i i) the vertical joints are broken properly from course to course . iii) For having full bond between perpendicular walls, it is necessary to make a slopping (stepped) joint by making the corners first to a height of 600 mm and then building the wall in between them. Otherwise , the toothed joint should be made in both the walls alternatively in lifts of about 450 mm.

13. MASONRY CONSTRUCTION WITH RECTANGULAR MASONRY UNITS (CLAUSE 8.0) Openings in Walls:- As openings in walls reduce their lateral load resistance and hence, should preferably be small and more centrally located . The guidelines on the size and position of opening are given in Table 4 of IS 4326:1993. Openings in any storey shall preferably have their top at the same level so that a continuous band could be provided over them , If opening are not provided according to the codal provision, they should be strengthened by providing reinforced concrete lining with high strength deformed bar of 8mm diameter as shown in Fig. 8. If a window or ventilator is to be projected out , the projection should be in reinforced masonry or concrete and tied together properly. The use of arches to span over the openings is a source of weakness and shall be avoided.Otherwise , steel ties should be provided.

14. Seismic Strengthening Arrangements All masonry buildings shall be strengthened in horizontal as well as vertical direction for improving the earthquake resistance. The strengthening arrangements are discussed in clause 8.4 of IS 4326:1993. 1. Horizontal Reinforcement 2. Vertical Reinforcement

15. Horizontal Reinforcement The horizontal reinforcing of walls is required for imparting them horizontal bending strength against inertia force. It also help in tying the wall together. In the exterior walls horizontal reinforcement helps in preventing shrinkage and temperature cracks. The following arrangements of horizontal reinforcement are necessary for earthquake resistant buildings. A) Horizontal bands or ring beam B) D owel bars

16. Horizontal bands or Ring beams A band is reinforced concrete or reinforced brick runner provided in the walls to tie them together and to impart horizontal bending strength to them. i ) Lintel Band i i) Plinth Band iii) Roof Band i v) Gable Band

17. Dowel Bars Dowel bars are provided in category D and E buildings. These are provided to improve the box action of walls. Steel dowel bars may be used at corners and T-junctions of walls at the sill level of windows to length of 900 mm from the inside corner in each wall. Such dowel may be in the form of U stirrups 8 mm dia. Where used, such bars must be laid in 1 : 3 cement-sand-mortar with a minimum cover of 10 mm on all sides to minimize corrosion.

18. Vertical Reinforcement Vertical steel at corners and junctions of walls, which are up to 340 mm (brick ) thick, shall be provided as specified in Table 7 of IS4326:1993. For walls thicker than 340 mm the area of the bars shall be proportionately increased . The amount of vertical steel depends upon number of storeys and category of building. No vertical steel need be provided in category A buildings . The vertical reinforcement should be properly embedded in the plinth masonry and roof slab or roof band.

19. Vertical Reinforcement The vertical reinforcement should pass through the lintel bands and floor slabs or floor level bands in all storeys . Vertical reinforcement for window and door openings should start from foundation of floor and up to lintel band. Typical details of providing vertical steel in brickwork masonry with rectangular solid units at corners and T-junctions are shown in Fig. 12 of IS4326:1993.

20. THANK YOU………..